The good news is the percentage of polluted lakes, rivers and streams in Iowa that are able to be assessed every two years decreased slightly from 2014 to 2016, according to a new draft report from the Iowa Department of Natural Resources.
The bad news is more than half Iowa’s assessed water bodies still are impaired by pollution that can limit recreation, kill fish and cost a lot of money to clean for drinking.
“One out of two waters tested in Iowa is impaired,” said Susan Heathcote, water program director for the Iowa Environmental Council. “That’s a concern we should be focusing on. Why is that the case?”
There are 750 bodies of water with 1,096 impairments on Iowa’s draft 2016 list of impaired waters the DNR will report to the U.S. Environmental Protection Agency next month. This compares with 736 lakes, rivers and streams with 1,062 impairments on the final list for 2014.
To be considered impaired, a river, stream, lake or wetland has failed to meet water quality standards for one or more of its intended uses, such as drinking, recreation or supporting aquatic life.
Although the number of impaired waters increased in two years, the DNR points out this is likely due to more monitoring, not necessarily worsening water quality.
“In general, when the amount of monitoring data increases, the number of waters on the Impaired Waters list also increases,” the DNR said in an online summary.
The share of assessed waters considered impaired went down from 55.9 percent on the 2014 final list to 54.4 percent for the 2016 draft. More impaired water bodies may be added through feedback Iowans are asked to submit by May 29.
The largest cause of impairments for Iowa streams and rivers assessed for 2016 is bacteria, which accounts for nearly half the 813 stream and river impairments, followed by biological and fish kills. Algae growth is the leading cause of 283 impairments for lakes, reservoirs and wetlands, the DNR reported.
Since 2006, the DNR has issued 185 beach advisories for high levels of microcystin, a toxin produced by blue-green algae. Because the toxins can cause gastroenteritis, skin irritation and allergic responses, as well as potentially life-threatening liver damage, the DNR advises against swimming at state park beaches when the advisories are issued, and monitors local beaches when the notices are in place.
The algae blooms are caused by a combination of nitrogen or phosphorus pollution, which can come from natural causes and fertilizer runoff.
The 2016 draft impaired waters list shows 109 fish kills, with more than 40 caused by animal waste, the DNR reported.
The DNR isn’t able to assess all Iowa lakes, rivers and streams every two years because of budget constraints. For 2016, 52 percent of rivers, 61 percent of lakes and reservoirs and 83 percent of wetlands were assessed.
The DNR is seeking public comment on the Category 5 impaired waters. To see the list go to: programs.iowadnr.gov/adbnet/Assessments/Summary/2016. To comment, send email to Dan Kendall at email@example.com.
l Comments: (319) 339-3157; firstname.lastname@example.org